Up to now, an optical disc having a guide groove, termed circling a pre-groove, has been known. If this pre-groove is formed, the groove and/or the land (area sandwiched between neighboring turns of the groove) becomes a recording track. By this pre-groove, formed in the optical disc, the disc driving side, responsible for recording and/or reproduction, is able to detect components of both edges of the recording track from the reflected laser light to effect servo control so that the laser light will be illuminated centrally of the two edges.
There has so far been known an optical disc in which the pre-groove is caused to meander in meeting with the wobble signal corresponding to FM modulated or PSK modulated carrier signal. In the modulating components of the wobble signal, there is contained e.g., the physical address information of the recording track at the recording positions of the wobble signal. So, the disc driving side, responsible for recording and/or reproduction, is able to detect the wobble signal from signals representing fluctuating components of both edges of the recording tracks (so-called push-pull signals) to demodulate the address information contained in the wobble signal to perform address control of the recording and/or reproducing positions.
However, with the system of inserting e.g., the address information into the wobble signal corresponding to the FM modulated carrier signals, a problem is raised that address reproduction characteristics are deteriorated by cross-talk components from neighboring tracks. In the system of inserting e.g., the address information into the wobble signal by PSK modulating the carrier signal, there is raised a problem that higher harmonics at the phase change points are superimposed on the playback signals to deteriorate reproduction characteristics. Moreover, in the case of the PSK modulation, the higher harmonics components are contained, with the result that the circuit configuration of the wobble signal demodulating circuit becomes complicated.